data hierarchy

n : an arrangement of data consisting of sets and subsets such

that every subset of a set is of lower rank than the set

class hierarchy

A set of {classes} and their interrelationships.

One class may be a specialisation (a "{subclass}" or "{derived

class}") of another which is one of its "{superclasses}" or

"{base classes}".

When a {method} is invoked on an {object} it is first looked

for in the object's class, then the superclass of that class,

and so on up the hierarchy until it is found. Thus a class

need only define those methods which are specific to it, and

inherits methods from all its superclasses.

See also: {multiple inheritance}.

(1997-08-06)